1. Technical Field
The present invention relates to a technology of a relay node simulator that simulates a relay node that relays communication between a base station and a mobile communication terminal.
2. Background Art
Standardization of LTE-Advanced, which is further developed from LTE (Long Term Evolution), as a wireless access scheme of next-generation mobile communication system has been in progress using the Third Generation Partnership Project (3GPP). In LTE-Advanced, a relay technology, which performs regenerative relaying of a radio signal between a base station and a mobile communication terminal at a layer 3 level, has been reviewed. When applying a relay node in which this relay technology is used, expansion of efficient coverage has been expected at locations at which it is difficult to secure a wired backhaul line that connects devices such as a switching center and a wireless base station that make up a mobile communication system with a wire, or the like (Patent Document 1).
In such a relay node, there are cases where a wireless backhaul line between the base station and the relay node, and a wireless access line between the relay node and the mobile communication terminal are operated at the same frequency. In this regard, in a case where sufficient isolation is not secured between these lines, a transmitted signal is wrapped around to a reception unit of the relay node and causes interference. Therefore, in a case of operation in the same frequency, radio resources of the wireless backhaul line and the wireless access line are subjected to TDM (Time Division Multiplexing) and transmission and reception at the relay node are controlled not to be carried out simultaneously. In addition, in addition to the above-described configuration, a configuration in which signals are continuously output from the base station, and allocation of resource elements is controlled with respect to signals from the base station and signals from the relay node to prevent interference of these signals has been reviewed. However, the present invention is also applicable to this configuration. Hereinafter, the above-described time division multiplexing configuration will be described as an example.
However, the level of each signal may vary or several signals may be delayed depending on a positional relationship between the base station, the relay node, and the mobile communication terminal. For example, until reception by the mobile communication terminal, the level of a signal transmitted from the base station is attenuated in accordance with the distance between the base station and the mobile communication terminal. Similarly, until being received by the mobile communication terminal, a level of a signal transmitted from the relay node is attenuated in accordance with the distance between the relay node and the mobile communication terminal. In addition, in a case where several signals are delayed, interference may occur between these signals. Therefore, it is necessary to verify an operation of the mobile communication terminal that is a terminal to be tested on the assumption that a variation in a level of these signals or delaying occurs, and a simulator that simulates this environment has been required.